Cocking lock-up

ABSTRACT

Plate cocking is achieved on a printing machine in operating condition and even when running by imposing a true slewing movement on the leading edge of a plate by a lock-up reference jaw mounted for arcuate movements about a center spaced from the jaw by an amount approximately equal to the printing length of the plate. The trailing edge jaw is a floating jaw. The change in angle of the plate leading edge is &#39;&#39;&#39;&#39;ironed&#39;&#39;&#39;&#39; along the plate towards its trailing edge by operation of the machine.

United States Patent 1 Swordy et a1.

[ June 12, 1973 COCKING LOCK-UP [75] Inventors: Robert Swordy, Yate; William Peter Herring, Winterbourne, both of England [73] Assignee: Strachan & Henshaw Limited,

Speedwell, Bristol, England [.22] Filed: June 25, 1971 [21] Appl. No.: 156,876

[30] Foreign Application Priority Data July 28, 1970 Great Britain 36,486/70 [52] US. Cl. l0l/4l5.1, 101/378 [51] Int. Cl B411 l/28 [58] Field of Search l0l/4l5.1, 378;

[56] References Cited UNITED STATES PATENTS 2,973,710 3/1961 Hantscho l01/415.1 3,608,487 9/1971 Luehrs ..-101/415.l 3,191,532 6/1965 Hermach et al. l01/415.l 3,188,952 6/1965 Miller 101/415.1 3,151,553 10/1964 Norton 101/415.1 3,017,830 1/1962 Penner l01/415.1

2,775,198 12/1956 Johnson et a1 101/415.1 3,646,886 3/1972 Woessner et al. 101/415.1 1,765,530 6/1930 l-larrold 101/415.1 2,012,972 9/1935 Osborn 2,768,578 10/1956 Park et a1. 10l/415.1

FOREIGN PATENTS OR APPLICATIONS 1,183,583 3/1970 Great Britain 101/415.1

1,180,042 2/1970 Great Britain 1,127,904 9/1968 Great Britain [OI/415.1

Primary Examiner-William B. Penn Assistant Examiner-Eugene H. Eickholt AttorneyJones and Lockwood [57] ABSTRACT Plate cocking is achieved on a printing machine in operating condition and even when running by imposing a true slewing movement on the leading edge of a plate by a lock-up reference jaw mounted for arcuate movements about a center spaced from the jaw by an amount approximately equal to the printing length of the plate. The trailing edge jaw is a floating jaw. The change in angle of the plate leading edge is ironed along the plate towards its trailing edge by operation of the machine.

4 Claims, 4 Drawing Figures PAIENIEU JUN? 25975 3. ?38.268

SHEET 2 OF 4 1 COCKING LOCK-UP BACKGROUND OF THE INVENTION This invention relates to cocking lock-up assemblies and printing machines incorporating them.

Plate cocking is an adjustment made to a flexible plate stretched under tension round a printing roll in a printing machine which causes a change of angle relative to the axis of the roll of at least part of the plate. The ends of the plate are held in a lock up assembly in the cylinder. In the past this type of adjustment has always been performed with the printing machine stationary or with the printing plate not under tension and since it is an empirical adjustment, the effect of which can only be seen in the printed results of working machine, this could entail repeated startings and stoppings of the machine.

One such prior proposal is seen in US. Pat. No. 3,456,588 (Brodie). I-Iere, cocking adjustment can be carried out while the plate ends are still clamped in the lock-up and while the plate remains under radial pressure. However, the plate cannot remain under its circumferential tension, and the press is thus not in its normal operating condition. This is thought to be because in that proposal (1) the trailing edge of the plate is adjusted and (2) the adjustment is a sideways (axial) adjustment which is only given a slewing (cocking) component by virtue of the presence between the trailing and leading edge jaws of the inextensible plate, taken with the pivoted mounting of the jaw assembly as a whole. The adjustment of the trailing edge of the plate has to travel back to the leading edge as the printing roll revolves. In effect, the presence of the radial pressure retards the adoption of the adjusted position.

SUMMARY OF THE INVENTION The present invention attacks the problem differently. It is the leading edge of the plate which is adopted as the reference edge and which is adjusted for cocking action. The actionis induced by the mounting of the jaw itself, and does not depend on the provision of a plate between itself and a pivoted, non-axiallyadjustable leading edge jaw, to convert a sideways (axial) motion into a cocking (slewing) adjustment.

The present invention provides in one aspect a printing machine in which cocking adjustment of a plate mounted on a printing cylinder of a machine may be operable during working rotation of a printing cylinder. In this machine, therefore, cocking adjustment may be made without stopping the machine or releasing the tension exerted on the plate by the lock-up, and enabling more or less immediate inspection of the results of the adjustment. It is the leading edge jaw that is adjusted, so that the action of the impression roll on the plate, under printing pressure, is to iron the adjustment towards the trailing end of the plate and speed the adoption of an adjusted position by the plate.

The leading edge jaw is constrained by its mounting in the lock-up assembly to execute an arcuate slewing action, i.e. the jaw movesas a chord to an arc of a circle. A preferred radius of this circle is the printing length of the plate, (substantially equal to the circumferential length of the printing cylinders). One preferred mechanism for achieving the cocking adjustment of the jaw is a linkage which includes a transmission rod passing axially of and within the shaft of the printing cylinder and drivable from beyond a side plate of the printing machine to cause relative displacement of the transmission rod and the shaft, the relative displacement causing the cocking adjustment of the movable jaw, this jaw being opposed by a floating jaw which accommodates to changes of position in the cocking aw.

The leading edge jaw is opposed by any floating jaw, see e.g. US. Pat. Nos. 3,191,532 and 3,359,899. It is preferred, however, that the jaw construction is, so far as the retention of the plate ends in the assembly is concerned, as disclosed and claimed in the Complete Specification of our co-pending United Kingdom Patent application No. 1,231,188.

A Particular embodiment of the invention will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a section on line I-I of FIG. 2 in a plane normal to the axis of rotation of a printing cylinder on which a lock-up assembly is mounted.

FIG. 2 is a section on the line II-II of FIG. 1 but with a cam rod omitted.

FIG. 3 is a section along the axis of the cylinder and showing mounting and drive arrangements of the cocking mechanism, and

FIG. 4 is a section (on a smaller scale than FIG. 1) on the line IVIV of FIG. 3.

Referring first to FIG. 1 there is shown a lock-up as sembly 1 for a flexible printing plate which is claimed in the Complete Specification of our co-pending United Kingdom Patent application No. 1,231,188, which assembly 1 is mounted in a parallel sided channel in a printing cylinder 2. Although the present embodiment is of a lock-up assembly of which the plate holding part is according to our said co-pending Application the present invention is applicable to lock-ups of other forms which are capable of cocking adjustment. Undercut jaws 3 and 4 of the assembly define a narrow slit 5 of which the median plane 6 is shown in dotted line and is a diametrical plane from the axis 6 of the cylinder 2. A flexible plate 56 may be wrapped around the cylinder with its inturned flange end 57 at the leading edge being inserted between the jaw 4 and one side 7 of the resilient divider 8 which partly occupies the mouth 5 of the slit. The trailing edge 58 of the plate is, after the plate has been wrapped around the cylinder, inserted between the jaw 3 and the part 9 of the divider which opposes it. An outturned lip of the divider is in closest proximity to the trailing edge of the plate, when that has been thus inserted.

The leading edge of the plate is, of course, that edge of the plate which first passes a given point in space at the cylinder on which it is mounted rotates in working rotation and is then followed by the printing area of the plate and finally by the trailing edge.

The jaw 3 is housed in an undercut portion of a block 12 in which are inserted plugs 13 (only one is shown) which takes the reaction from strong springs 10 (again only one being shown) which abut at their other ends on the jaw 3. The jaw 3 is pivoted by means of a shaft 11 to which it is secured and which works in over-size bearings in a base portion 14 of the block 12. The movement of the jaw 3 under the influence of the springs 10 is permitted or prevented by a cam rod 15 having cam faces 16 intermittently along its length which interact with ridge cam followers 17 on the appropriate face of the jaw 3.

Upon release of jaw 3 so that it moves under the influence of the springs 10, pressure is transmitted direct from jaw to jaw via the inturned end flanges of the plate and the divider 8 to hold the plate to the cylinder and stretch it round it.

Alternately with the cam faces 16 along the axial length of the rod 15, and disposed at right-angles to those cam faces are scallops 18 which register with recesses between the ribs 17. The provision of these recesses and scallops allows access through the mouths of the slot (which is not continuously occupied by the divider) to bolts which hold the whole lock-up assembly into the plate cylinder and which penetrate into the cylinder along the line generally indicated at 20.

As shown in FIG. 1 the cam rod is holding the jaw 3 back against the spring tension. The thrust exerted on the cam rod through the jaw is taken up by a post 21 which is massively secured at 22 in a base portion 23 of a second housing part 24 which accommodates jaw 4 analogously with the block 12 accommodating jaw 3. Jaw 3 is a floating jaw when it is released from constraint by the cam rod 15; it is free to follow under the influence of the springs 10, changes in e.g. length of the plate or position of the jaw 4, by pivoting and radial movements on its shaft 11.

The two base portion 23 and block 12 are held together by screws 25 lying in a plane perpendicular to the median plane 6 of the slot.

The cocking jaw 4 is received between downwardly facing wall 26 and an upwardly facing wall 27 of the part 24, these walls being in planes perpendicular to the diametrical plane 6. The jaw 4 has a part 28 which fits slidingly between these walls so that any twisting moment of the jaw 4 about an axis parallel to that of the cylinder 1 (Le. any which would be represented by-an upward movement of the part of the jaw at the mouth of the slot) is taken up by reaction with these surfaces 26 and 27. The cocking jaw 4, which receives the leading edge of the printing plate, executes arcuate cocking movements while the plate is maintained under tension. There are four slots 29 to 32 arranged in the base portion 23 of the part 24, the slots being arranged on an arc of a circle centered well beyond the other jaw, preferably being centered at the far end of the printing length of the plate (which gives an effective radius for the circle approximately equal to the circumferential .length of the printing cylinder) the center of the circle being at the middle plane of the axial length of the cylinder. The side walls of the slots are also arcs centered on the same point. Pins 33 project downwardly from the part 28 of the jaw 4 and are engaged screwthreadedly by cubic sliders 34 which slidingly engage the arcuate walls of the slots 29 to 32. Thus if the cocking jaw 4 is pushed generally in the axial direction of the cylinder it moves as a chord of an arc of a circle, and slews and executes some sideways motion. An arcuate movement of this type is apt to produce a more correct cocking action on a flexible plate than a simple slewing or pivoting motion which does not have any axial component, and to induce a correct cocking action in a plate. Drive mechanism for causing this motion is positioned generally at 35, FIG. 2, but is seen more clearly in FIGS. 3 and 4.

Referring to FIG. 4 a clevis 36 is mounted on a transverse shaft 37 so that where it engages a trunnion 38 secured to the jaw 4'it causes the required generally axial motions of the cocking jaw which are translated by the slots 29 to 32 and blocks 34 which engage them into the arcuate cocking motions. Pivoting motion of the clevis is causes by engagement of a fork 41 at its lower end with a plate 42 mounted on a transmission shaft 39 which lies on an axis of the shaft (FIG. 3) of the cylinder 2, which shaft is hollow. The shaft is supported in an ordinary bearing arrangement 43 on the machine frame. The transmission shaft 39 is constrained against rotation relative to the shaft 40 by a screw 44 engaging a key-way 45 in the shaft 39 but it is axially movable relative to that shaft by a drive arrangement which includes a pinion 46 driven through a gear train'47, 48, from a slow speed synchronous electric motor 49. Rotation of the pinion 46 is transmitted to a screw-threaded boss 50 which is arranged coaxially with the shafts 39 and 40, in a screw-threaded bush 51 mounted on a stationary side plate 52 of the machine. The axial movement of the pinion 46 which is caused when it rotates is due to this screw-threaded engagement between the bush 51 and boss 50 and is transmitted to the transmission shaft through thrustbearing 54 borne on a sleeve 55 on the end of a transmission shaft 39. Thus the shaft 39 rotates with the cylinder 2 and its shaft 40 but can be driven axially at any time by rotation of the pinion 46 which rotation is of course entirely independent of the rotation of the cylinder 2 since the thrust-bearing 54 permits free rotation of the pinion 46 and shaft 39 relative to each other.

The ability of this construction to work and cause cocking adjustment of the plate held by the lock-up assembly even while the cylinder 2 is rotating during a normal printing operation is highly advantageous.

Slots such as 29 to 32 need not lie in a single circular arc provided that all such arcs are centered on a single point.

What we claim is;

l. A printing machine having a plate cylinder having an axis of rotation, a plate lock-up in the plate cylinder, a flexible plate stretched around the plate cylinder, an impression roll pressing against the plate at a nip between the plate cylinder and the impression roll, the plate having two intumed ends, the inturned ends being a trailing edge and the other being a leading edge of the plate, a first jaw of the lock-up engaging the leading edge end and a second jaw of the lock-up engaging the trailing edge end, the first jaw being an adjustable cocking reference jaw, adjustable generally along the axis of the cylinder and mounted to the lock-up by means imposing on it a generally axial arcuate said adjusting motion, the center of arc of said motion being at a distance from the jaw about equal to the circumferential length of the cylinder, the second jaw being a floating jaw, whereby angular adjustment imposed on the leading edge end of the plate by the first jaw is ironed along the plate by the impression roll as the plate passes through the nip and is accommodated by the floating jaw engaging the trailing edge end of the plate, to achieve cocking adjustment of the plate under operating conditions. 2. A printing machine according to claim 1 wherein the said means includes an array of slots and lugs engaging with the slots, the slots being arranged in at least one are of a circle on a center spaced from the jaw a distance about the same as the printing length of the plate.

3. A printing machine according to claim 1 wherein the plate is engaged between the jaws by a resilient divider.

screwthreadedly engaging a boss rotationally independent of but axially constrained to the said shaft, and a motor to drive the bush in rotation, whereby the boss and hence the shaft may be axially driven.

i 3 i t i 

1. A printing machine having a plate cylinder having an axis of rotation, a plate lock-up in the plate cylinder, a flexible plate stretched around the plate cylinder, an impression roll pressing against the plate at a nip between the plate cylinder and the impression roll, the plate having two inturned ends, the inturned ends being a trailing edge and the other being a leading edge of the plate, a first jaw of the lock-up engaging the leading edge end and a second jaw of the lock-up engaging the trailing edge end, the first jaw being an adjustable cocking reference jaw, adjustable generally along the axis of the cylinder and mounted to the lock-up by means imposing on it a generally axial arcuate said adjusting motion, the center of arc of said motion being at a distance from the jaw about equal to the circumferential length of the cylinder, the second jaw being a floating jaw, whereby angular adjustment imposed on the leading edge end of the plate by the first jaw is ironed along the plate by the impression roll as the plate passes through the nip and is accommodated by the floating jaw engaging the trailing edge end of the plate, to achieve cocking adjustment of the plate under operating conditions.
 2. A printing machine according to claim 1 wherein the said means includes an array of slots and lugs engaging with the slots, the slots being arranged in at least one arc of a circle on a center spaced from the jaw a distance about the same as the printing length of the plate.
 3. A printing machine according to claim 1 wherein the plate is engaged between the jaws by a resilient divider.
 4. A printing machine according to claim 2 wherein means for driving the first jaw relative to the lock-up include a shaft coaxial with the cylinder, the shaft being constrained to rotate with the cylinder but being axially moveable independently of it, a screw-threaded bush screw-threadedly engaging a boss rotationally independent of but axially constrained to the said shaft, and a motor to drive the bush in rotation, whereby the boss and hence the shaft may be axially driven. 